From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [PATCH v8 4/5] libxc: Provide set_xen_guest_handle_offset macro Date: Fri, 8 May 2015 15:57:53 +0100 Message-ID: <1431097073.2660.492.camel@citrix.com> References: <1430936102-3465-1-git-send-email-boris.ostrovsky@oracle.com> <1430936102-3465-5-git-send-email-boris.ostrovsky@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1430936102-3465-5-git-send-email-boris.ostrovsky@oracle.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Boris Ostrovsky Cc: elena.ufimtseva@oracle.com, wei.liu2@citrix.com, stefano.stabellini@eu.citrix.com, andrew.cooper3@citrix.com, dario.faggioli@citrix.com, ian.jackson@eu.citrix.com, xen-devel@lists.xen.org, jbeulich@suse.com, keir@xen.org, dgdegra@tycho.nsa.gov List-Id: xen-devel@lists.xenproject.org On Wed, 2015-05-06 at 14:15 -0400, Boris Ostrovsky wrote: > Add set_xen_guest_handle_offset() macro that can be used for setting > xen_guest_handle to an offset into hypercall buffer. > > Signed-off-by: Boris Ostrovsky > --- > tools/libxc/include/xenctrl.h | 11 ++++++++--- > 1 files changed, 8 insertions(+), 3 deletions(-) > > diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h > index 8c8eae6..4e6f62c 100644 > --- a/tools/libxc/include/xenctrl.h > +++ b/tools/libxc/include/xenctrl.h > @@ -322,16 +322,21 @@ typedef struct xc_hypercall_buffer xc_hypercall_buffer_t; > * Set a xen_guest_handle in a type safe manner, ensuring that the > * data pointer has been correctly allocated. > */ > -#undef set_xen_guest_handle > -#define set_xen_guest_handle(_hnd, _val) \ > +#undef set_xen_guest_handle_offset This isn't strictly speaking needed since you aren't trying to override a version of this interface provided by the hypervisor headers. > +#define set_xen_guest_handle_offset(_hnd, _val, _off) \ > do { \ > xc_hypercall_buffer_t _hcbuf_hnd1; \ > typeof(XC__HYPERCALL_BUFFER_NAME(_val)) *_hcbuf_hnd2 = \ > HYPERCALL_BUFFER(_val); \ > (void) (&_hcbuf_hnd1 == _hcbuf_hnd2); \ > - set_xen_guest_handle_raw(_hnd, (_hcbuf_hnd2)->hbuf); \ > + set_xen_guest_handle_raw(_hnd, \ > + (_hcbuf_hnd2)->hbuf + (_off)); \ The hypervisor side guest_handle_add_offset equivalents operate in multiples of the type. If we can arrange that here too then I think that would be good. I think that means + (_hcbuf_hnd2)->hbuf + ((sizeof(*_val)*(_off))); \ Then the caller becomes e.g. set_xen_guest_handle_offset(sysctl.u.pcitopoinfo.devs, devs, processed); which is much nicer IMHO. Ian.